1. Field of the Invention
The present invention relates generally to sound source localization and, more particularly, to a method and apparatus for sound source localization wherein a sound source is localized using both microphones directly receiving sound signals from the source and microphones indirectly receiving sound signals.
2. Description of the Related Art
Microphones can be used in various ways according to their placement. For example, in sound enhancement, a microphone is used to amplify sound originating only from a particular speaker or position. In sound source localization, when a speaker talks, a microphone is used to locate the speaker. In source separation, when a number of speakers simultaneously talk, a microphone is used to separate the sound of a particular speaker from other sounds. In particular, active research has been conducted in sound source localization and its application.
Techniques for sound source localization are based on time difference of arrival (TDOA) estimation, on a steered beamformer delaying and summing individual signals captured by multiple microphones, or on high-resolution spectral estimation.
Localization accuracy is a very important performance measure in sound source localization employing an array of microphones. Performance of sound source localization depends upon the characteristics of the microphones, the number of microphones, their arrangement, the level of noise and reverberation, and the number of talking speakers.
High-quality and multiple microphones can heighten localization performance, and a high level of noise and reverberation can lower localization performance. Localization performance can be heightened through arranging microphones in a manner suitable for an application, and localization performance can be lowered with an increased number of talking speakers because of increased ambiguity.
Whereas a large number of microphones can lead to good localization performance, the number of installable microphones may be limited in some cases. Thus, it is necessary to provide a high-performance sound source localization technique employing a small number of microphones.